Electrical temperature-alarm.



No. 762,125. PATENTED JUNE 7, 1904. J, P. BOLTON.

ELECTRICAL TEMPERATURE ALARM. APPLICATION FILED JUNE 16.1902.

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UNITED STATES Patented June 1904.

PATENT OFFICE.

JOSEPH P. BOLTON, OF FRESNO, CALIFORNIA.

ELECTRICAL TEMPERATURE-ALARM.

SPECIFICATION forming part of Letters Patent No. 762,125, dated June 7, 1904.

Applicati fil d June 16, 1902. Serial No. 111,883. (No model.)

T0 0.6], whom 212% may conceiva- 7 Be it known that I, JosErH P. BOLTON, of Fresno, in the county of Fresno and State of California, have invented a new and useful Improvement in Electrical Temperature- Alarms, of which the following is a specification.

The object of my invention is to have an electric bell rung the moment the temperature falls to the freezing-point or to any desired degree.

Frosts cause incalculable damage to orchards and vineyards every year, and as an adjunct to various methods of frost-fighting now in use I have devised a simple and novel electric temperature-alarm in the nature of an attachment to the ordinary dial-thermometer which is designed to be set up in an orchard or vineyard and wired into a sleeping-apartment or to any other desired point and there connected to a bell to be rung whenever the temperature falls'to the danger-point.

My invention consists in the novel construction of the contact attachment and its combination with the dial-thermometer, which I will now proceed to describe with reference to the drawings, in which Figure 1 is a front elevation of the entire device. Fig. 2 is an enlarged cross-section of the thermometer and its attachment on line 5 6 of Fig. 1. Fig. 3 is a detail plan view of the circular insulation-band and its attached contact-spring, and Fig. 4: is a cross-section of the same on line 7 8 of Fig. 3.

Similar letters of reference indicate the same parts throughout the several views.

A is a metallic dial-thermometer of that well-known form in which thin strips of two metals having different rates of expansion and contraction are soldered or otherwise rigidly fastened. One end of such compound bimetallic strip is firmly anchored to a fixed point, and the other end from the differential rate of expansion moves according to the rise and fall of temperature and through a lever or gears turns a shaft bearing an index-hand a, that traverses a graduated dial and indicates thereon the temperature. Such thermometer is well known and requires no special illustration. Vith this thermometer is combined my attachments, and to it are connected through circuit-wires an electric bell O, a battery B, and a switch O.

I will now describe the novel features of my invention.

a is a circular ring or insulation-band of hard rubber or vulcanized fiber about onefourth of an inch wide by one-sixteenth of an inch thick passing around the inside of the thermometer-casing between the glass front g and the graduated dial it and separating the two.

(Z is a brass contact-spring about one-fourth of an inch wide attached to the concave side of the insulation-ring e by means of a small screw m. The said contact-spring (Z is bent downward at the tip far enough so that it will be touched by the hand a when the latter is directly under it.

The back i of the thermometer is a thin plate of j apanned iron, to which abinding-post c is connected by direct contact. I) is another binding-post attached to the said back 2', but insulated from it by non-conducting washers 7i) and An insulated copper wirefconnects the contact-spring (Z through the small screw m with the binding-post b.

j is a circular band of perforated tin separating the dial from the back 2 thereby leaving space for the thermometer mechanism and acting also as a conductor from binding-post c and back i to dial-plate 71/ and indicator-hand a, which is mounted on the dial.

Then the indicator-hand is in the position shown in Fig. 1, the electric circuit in this position is open; but when the hand attains the dotted position shown by a it comes in contact with the spring (Z, thereby closing the circuit and ringing the bell.

It will be understood that the position of the contact-spring (Z in relation to the dial may be changed as desired to sound the alarm at any desired temperature, for which purpose the insulation-ring a may be simply turned or rotated to bring the contact-spring (Z over any desired temperature marking on the dial. The insulation-ring 0 also serves to hold the glass face in position properly spaced away from the front of the dial.

I claim 1. The combination with a thermometer having a metallic dial, a metallic back plate having electrical connection with the dial, a pointer movable over the dial, and in direct electrical connection therewith, a bindingpost in electrical connection with the back plate anda second binding-post insulated from the back plate, of a transparent covering for the diaL-a ring of insulating material between the dial and the transparent covering, a contact-piece carried by the ring and projecting into the path of the pointer, and an electrical connection between the contact-piece and the last-mentioned binding-post.

2. The combination with a thermometer having a metallic dial, a metallic back plate having electrical connection with the dial, a pointer movable over the dial, and in direct electrical connection therewith, a bindingpost in electrical connection with the back plate and asecond binding-post insulated from the back plate, of a transparent covering for the dial, a ring of insulating material disposed edgewise between the dial and the transparent covering, a spring contact-piece carried by the ring and projecting into the path of the pointer, and an electrical connection between the contact-piece and the last-mentioned binding-post.

3. The temperature-alarm, comprising a dial-thermometer with index-hand, a circular non-conducting ring arranged concentrically in front of the dial and bearing a contactspring adapted to be touched by the indexhand, and a glass face retained between the edges of the thermometer-casing and the nonconducting ring substantially as and for the purpose described.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

JOSEPH P. BOLTON.

Witnesses:

LOUIS ROMAN, HENRY H. WELSH. 

